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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 13th February 2018, 04:11 AM   #99791
RNMarsh is offline RNMarsh  United States
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John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by simon7000 View Post
RNM,

Not really sure, unmarked except for value. As I have learned from measurements over the years even with the same dielectric higher voltage film parts work better due to less dc/dt.
.
Very true. Higher voltage caps measure better in almost every parameter. This is especially true for polar and bipolar electrolytic type. Also, 105C rated caps are much better than 85C caps.

I always use 105C rated when electro types are needed. They also generally have longer life.


THx-RNMarsh

Last edited by RNMarsh; 13th February 2018 at 04:13 AM.
 
Old 13th February 2018, 05:17 AM   #99792
dadod is offline dadod  Croatia
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Originally Posted by DPH View Post
Totally not making fun of you in the least (I admire your clarity in what is not your native tongue!) but "twitter" versus tweeter amused me.

And, yes, I'm also doing active but made one of the poles a series capacitor for insurance as well.
Yes that's funny, my bad.
 
Old 13th February 2018, 01:38 PM   #99793
PMA is offline PMA  Europe
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Originally Posted by DPH View Post

And, yes, I'm also doing active but made one of the poles a series capacitor for insurance as well.
A new kind of insurance?
 
Old 13th February 2018, 01:48 PM   #99794
scottjoplin is offline scottjoplin  Wales
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Originally Posted by TheGimp View Post
Aren't those gold over silver over copper relays small signal relays for analog switching, not for speaker switching where there are potentially large currents involved.

Similar to the AXICOM IM07 series.
What relays are you referring to?
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Old 13th February 2018, 02:04 PM   #99795
TheGimp is offline TheGimp  United States
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The ones Mr. Marsh was talking about in post 99782.
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Old 13th February 2018, 03:21 PM   #99796
DPH is offline DPH  United States
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A new kind of insurance?
Solely depends on capitalization. The chap I found keeps a close eye on my volume control for sure, haha.
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Old 13th February 2018, 08:20 PM   #99797
simon7000 is offline simon7000  United States
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More fun. A 1.8 uF 160 VAC 250VDC Bennic brand metalized polypropylene capacitor into a 10,000 ohm 1% metal film 1/4 watt resistor. 5 volts RMS at 20 hertz and .5 volts RMS at 200 hertz. DC coupling out of the AP. Nicely shows the harmonic and intermodulation distortion. I will run the test again tomorrow to be sure it holds up.

Last edited by simon7000; 13th February 2018 at 08:26 PM.
 
Old 13th February 2018, 10:20 PM   #99798
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by simon7000 View Post
More fun. Nicely shows the harmonic and intermodulation distortion. I will run the test again tomorrow to be sure it holds up.
Nicely, really? Since the 60Hz can't be differentiated from hum no claims to its origin can be made and since 20 and 200 are exactly divisible there is no definitive proof of IM here either. You do love confounders don't you? Besides if the 60Hz is hum everything is -115dB or better not exciting.

EDIT - That's an 8.8Hz corner so there is considerable AC voltage on the cap and the fundamental magnitude is off on the plot.
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Last edited by scott wurcer; 13th February 2018 at 10:27 PM.
 
Old 13th February 2018, 10:21 PM   #99799
Max Headroom is offline Max Headroom  Australia
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The relay coil produced magnetic field is intimately close to the relay switch conductors and contacts.
What is the effect of relay coil stray magnetic field on signals passing through a typical relay ?.
Ditto permanent magnets in relays (bistable relays).

Dan.

Last edited by Max Headroom; 13th February 2018 at 10:36 PM.
 
Old 13th February 2018, 10:25 PM   #99800
billshurv is online now billshurv  United Kingdom
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John Curl's Blowtorch preamplifier part II
Linear audio 13 looked at that. Mainly focussed on reed relays, but measured std ones as well. The std ones were waay down in the weeds. This was looking at small signal work not power amp outputs, but at power amp levels the effects will be even less.
 

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